/Engine/Source/Runtime/Core/Public/Math/TransformNonVectorized.h
Transform a direction vector by the inverse of this transform - will not take into account translation part. If you want to transform a surface normal (or plane) and correctly account for non-uniform scaling you should use TransformByUsingAdjointT with adjoint of matrix inverse.
[TVector](API\Runtime\Core\Math\TVector)< T > InverseTransformVector ( const [TVector](API\Runtime\Core\Math\TVector)< T > & V ) const